In my ISA server which is in my domain i have installed Mail Essentials(GFI) software for spam mail control and found in the "Directory harvesting" -""Enable Directory Harvesting protection" - "Use native active directory lookup" option is enabled . I have installed a secondary mail relay server(which is my DMZ and not in domain), I have installed Mail Essentials in that server But in the Mail Essentials "Dierectory Harvesting" option When i select "Enable Directory Harvesting protection" I have found "Use native active directory lookup" option is disable. Please suggest me how can i enable "Use native active directory lookup" option. Should i join secondary mail relay server in domain soasto i will get
"Use native active directory lookup" enable or I need any other configuration. Please suggest me.